1. Field of the Invention
The present invention relates to a thermoelectric module, and particularly to a thermoelectric module including a thermoelectric element and an electrode.
2. Description of the Background Art
Generally, a thermoelectric module is configured such that an electrode is joined to an end face of a thermoelectric element. Such a thermoelectric module is disclosed, for example, in Japanese Patent Laying-Open No. 2000-101152.
In the thermoelectric module disclosed in the above-mentioned patent document, however, since the electrode is joined to a part of the end face of the thermoelectric element, the area of the electrode joined to the end face of the thermoelectric element becomes relatively small. This poses a problem of decreasing the effect of heat transfer between an object and the thermoelectric element. In order to improve the effect of heat transfer between the object and the thermoelectric element, it is conceivable to join the electrode to the entire end face of the thermoelectric element.
This however also causes the following problem. Specifically, when a current is caused to flow through the thermoelectric module, one end face of the thermoelectric element is cooled while the other end face opposite to one end face is heated. In this case, since a temperature difference occurs in the thermoelectric element between one end face and the other end face, unbalanced deformation tends to occur in one end face and the other end face of the thermoelectric element in accordance with the thermal expansion coefficient thereof. However, since electrodes are joined to one end face and the other end face, respectively, of the thermoelectric element, deformation of the thermoelectric element is prevented by these electrodes. Consequently, thermal stress occurs in the thermoelectric element. Since this thermal stress is noticeably concentrated in four corners of the end face of the thermoelectric element, these four corners of the end face of the thermoelectric element may be destroyed by the thermal stress.